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There's a draft like this in TLP.
We can never truly eradicate the coronavirus, but we can suppress its threat like influenza
Huh, okay then. I thought we'd have this one for sure already.
Well, that’d be jus’ a waste. Why would ya want to deprive the world of such anomaly as yourself?
Alligoric dream??? James and the Giant Peach (the movie [not the book]): James dreams he is a caterpillar and caricatures of his aunts gas him to death, which is an allegory to the abuse of his aunts mixed in with the absurd death of his parents. So it is definitely a plot device, whether or not it is a trope I don't know.
Edited by kinnlm
Mental Monster
is the YKTTW draft 4tell0life4 mentioned.
Stock Monster Symbolism when it's a real monster that mirrors their own issues- an abuse victim having to face down a possessive Humanoid Abomination, a drug addict facing off against vampires driven by Horror Hunger, etc.
Tulpa when they (often inadvertently) bring their dream-monster to life.
When some kind of creature, usually appearing in the dreams of a character, represents/is actually a metaphor for something else "monstrous" in their life, i.e someone who has abused the character or one of the character's addictions.